The present invention relates in general to plastic tubing and, more particularly, to an apparatus for making helically wound and helically ribbed plastic tubing.
Still more particularly, the invention contemplates an apparatus which includes means for extruding a plastic strip having a longitudinal rib on one side thereof, and which includes winding means for helically winding the ribbed strip about an axis into a tube with one edge of each convolution overlapping and heat bonded to an edge of a preceding convolution. The apparatus also includes means for cooling the tube both internally and externally after heat bonding of adjacent convolutions has been completed.
Any suitable heat bondable plastic may be used. As examples, the invention may utilize such thermoplastics as polyethylene, polyvinyl chloride, or the like.
Britton et al U.S. Pat. No. 3,122,171, issued Feb. 25, 1964, discloses a conventional helically wound and helically ribbed plastic tubing of the foregoing general nature, while Britton et al U.S. Pat. Nos. 3,243,328 and 3,301,734, respectively issued Mar. 29, 1966 and Jan. 31, 1967, respectively disclose a prior method and a prior apparatus of making plastic tubing of this nature.